1. Field of the Invention
This invention relates to RF transceiver design, and, more particularly, controlling the output power of an RF transmitter.
2. Description of the Related Art
Radio frequency (RF) transmitters/receivers are used in a wide variety of applications, including wireless network interfaces, mobile telephones, and Bluetooth interfaces. RF transceivers also feature prominently in wireless audio technology directed to headphones and earphones, home audio/theater systems and speakers, portable audio/media players and automotive sound systems. Robust, high-quality audio and low-power RF capability can make it possible for consumer and automotive original equipment manufacturers (OEMs) to integrate wireless audio technology into portable audio devices and sound systems. Overall, various RF technologies lend themselves to a number of applications in the consumer world to create high-fidelity home theater environments and distribute audio in the home and other environments.
A radio communication system typically requires tuned circuits at the transmitter and receiver, all tuned to the same frequency. The transmitter is an electronic device that propagates an electromagnetic signal, representative of an audio signal, for example, typically with the aid of an antenna. An RF transceiver is designed to include both a transmitter and a receiver, combined to share common circuitry, many times appearing on the same piece of integrated circuit (IC) chip. If no circuitry is common between transmit and receive functions, the combined device is referred to as a transmitter-receiver. Transceivers usually combine a significant amount of the transmitter and receiver handling circuitry.
RF Transceivers use RF modules for high-speed data transmission. The circuits in a digital RF architecture can operate at frequencies of up to 100 GHz. In most systems, digital processors or processing elements (which are oftentimes software-programmable) are used to perform conversion between digital baseband signals and analog RF, and oscillators are used to generate the required periodic signals. Many RF circuits make use of a voltage-controlled oscillator (VCO), in which the oscillation frequency is controlled by a voltage input, and the oscillation frequency is controlled through an applied DC voltage. Another common element of RF transceivers is the RF power amplifier, which is a type of electronic amplifier used to convert the low-power RF signal into a larger signal of significant power, typically for driving the antenna of the transmitter. RF amplifiers are usually designed to have high efficiency, high output Power compression, good return loss on the input and output, good gain, and optimum heat dissipation. Oftentimes, however, wireless audio systems also have a high demand for low power operation, for example when operating on battery power. In order to prolong the battery life of such a wireless audio system, it is desired to improve the power efficiency of the system.
Other corresponding issues related to the prior art will become apparent to one skilled in the art after comparing such prior art with the present invention as described herein.